Running A Motor In Star Mode At 60% Load

And on top of all that, your math is wrong. In Star, the capacity of the motor is not reduced TO 60%, it is reduced BY 67%, to 33% of it's design rating. In Star, any load of more than 12kW will overload your motor and fry it.

And.... there is almost zero real energy savings. An AC motor only uses what the load demands of it, plus a little bit of losses in making the iron and copper into a motor. The load is the load, regardless of how you connect the motor. So the only POSSIBLE energy savings come from a slight decrease in a portion of the losses. Losses in an AC motor are divided into 4 parts, not equally. Most of the losses are I²t losses, so they are directly related to load / torque, meaning those losses are going to be the same regardless of your connection. A small portion is windage; same, and friction; same. The only thing you can save on is a percentage of the magnetic losses, which are related to the voltage applied. So in Star, the voltage across the coils is 58% of what it is in Delta, so those losses are reduced by 42%. But those losses only account for about 10% of the total losses, which on a motor is maybe 10-15% of the total energy. So running in Star might save you 42% of 10% of 15% at best. That is .04%. Not 4%, 0.04%! Not even worth the cost of doing it and running the risk of stalling.

Simple truth to remember for ALL schemes about saving energy:

You can ONLY save what is WASTED, not what is USEFUL.